Applications of the Peach-Koehler Force in Liquid Crystals

Fuente: arXiv
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Main Authors: Long, Cheng, Selinger, Jonathan V.
Format: Preprint
Published: 2023
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author Long, Cheng
Selinger, Jonathan V.
author_facet Long, Cheng
Selinger, Jonathan V.
contents In solids, external stress induces the Peach-Koehler force, which drives dislocations to move. Similarly, in liquid crystals, an external angular stress creates an analogous force, which drives disclinations to move. In this work, we develop a method to calculate the relevant angular stress either analytically or numerically, and hence to determine the force on a disclination. We demonstrate this method by applying the Peach-Koehler force theory to four problems: (a) Single disclination in a liquid crystal cell between two uniform in-plane alignments perpendicular to each other. (b) Array of disclinations in a liquid crystal cell with patterned substrates. (c) Pair of disclinations in a long capillary tube with homeotropic anchoring. (d) Radial hedgehog or disclination loop inside a sphere with homeotropic anchoring, and its response to an applied magnetic field. In all of these problems, the Peach-Koehler force theory predicts the equilibrium defect structure, and the predictions are consistent with the results of minimizing the total free energy.
format Preprint
id arxiv_https___arxiv_org_abs_2309_15315
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Applications of the Peach-Koehler Force in Liquid Crystals
Long, Cheng
Selinger, Jonathan V.
Soft Condensed Matter
In solids, external stress induces the Peach-Koehler force, which drives dislocations to move. Similarly, in liquid crystals, an external angular stress creates an analogous force, which drives disclinations to move. In this work, we develop a method to calculate the relevant angular stress either analytically or numerically, and hence to determine the force on a disclination. We demonstrate this method by applying the Peach-Koehler force theory to four problems: (a) Single disclination in a liquid crystal cell between two uniform in-plane alignments perpendicular to each other. (b) Array of disclinations in a liquid crystal cell with patterned substrates. (c) Pair of disclinations in a long capillary tube with homeotropic anchoring. (d) Radial hedgehog or disclination loop inside a sphere with homeotropic anchoring, and its response to an applied magnetic field. In all of these problems, the Peach-Koehler force theory predicts the equilibrium defect structure, and the predictions are consistent with the results of minimizing the total free energy.
title Applications of the Peach-Koehler Force in Liquid Crystals
topic Soft Condensed Matter
url https://arxiv.org/abs/2309.15315